Test failure: HandleEventShutdownInitiatedByTransport fails with AuthenticationException : Authentication failed because the remote party sent a TLS alert: 'UserCanceled'.

```
System.Net.Quic.Tests.QuicListenerTests.Listener_BacklogLimitRefusesConnection_ParallelClients_ClientThrows(backlogLimit: 10, connectCount: 10) [FAIL]
System.Security.Authentication.AuthenticationException : Authentication failed because the remote party sent a TLS alert: 'UserCanceled'.
Stack Trace:
/_/src/libraries/System.Net.Quic/src/System/Net/Quic/QuicConnection.cs(657,0): at System.Net.Quic.QuicConnection.HandleEventShutdownInitiatedByTransport(_SHUTDOWN_INITIATED_BY_TRANSPORT_e__Struct& data)
/_/src/libraries/System.Net.Quic/src/System/Net/Quic/QuicConnection.cs(771,0): at System.Net.Quic.QuicConnection.HandleConnectionEvent(QUIC_CONNECTION_EVENT& connectionEvent)
/_/src/libraries/System.Net.Quic/src/System/Net/Quic/QuicConnection.cs(806,0): at System.Net.Quic.QuicConnection.NativeCallback(QUIC_HANDLE* connection, Void* context, QUIC_CONNECTION_EVENT* connectionEvent)
--- End of stack trace from previous location ---
/_/src/libraries/System.Net.Quic/src/System/Net/Quic/Internal/ValueTaskSource.cs(176,0): at System.Net.Quic.ValueTaskSource.System.Threading.Tasks.Sources.IValueTaskSource.GetResult(Int16 token)
/_/src/libraries/System.Net.Quic/src/System/Net/Quic/QuicListener.cs(247,0): at System.Net.Quic.QuicListener.StartConnectionHandshake(QuicConnection connection, SslClientHelloInfo clientHello)
/_/src/libraries/System.Net.Quic/src/System/Net/Quic/QuicListener.cs(192,0): at System.Net.Quic.QuicListener.AcceptConnectionAsync(CancellationToken cancellationToken)
/_/src/libraries/System.Net.Quic/tests/FunctionalTests/QuicListenerTests.cs(348,0): at System.Net.Quic.Tests.QuicListenerTests.Listener_BacklogLimitRefusesConnection_ParallelClients_ClientThrows_Core(Int32 backlogLimit, Int32 connectCount)
/_/src/libraries/System.Net.Quic/tests/FunctionalTests/QuicListenerTests.cs(359,0): at System.Net.Quic.Tests.QuicListenerTests.Listener_BacklogLimitRefusesConnection_ParallelClients_ClientThrows_Core(Int32 backlogLimit, Int32 connectCount)
```

## Build Information
Build: https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_build/results?buildId=1588649
Build error leg or test failing: System.Net.Quic.Tests.QuicListenerTests.Listener_BacklogLimitRefusesConnection_ParallelClients_ClientThrows
Pull request: https://github.com/dotnet/runtime/pull/133441

## Error Message

**DO NOT USE JSON BELOW IF THIS IS A BUILD BREAK** otherwise build analysis will allow pull requests to merge that break the build worse. For a build break, do not use this issue form. Make a regular new issue.

Fill the error message using [step by step known issues guidance](https://github.com/dotnet/arcade/blob/main/Documentation/Build%20Analysis/KnownIssueJsonStepByStep.md).

```json
{
"ErrorMessage": ["AuthenticationException","HandleEventShutdownInitiatedByTransport"],
"ErrorPattern": "",
"BuildRetry": false,
"ExcludeConsoleLog": false
}
```

### Known issue validation
**Build: :mag_right:** https://dev.azure.com/dnceng-public/public/_build/results?buildId=1588649
**Error message validated:** `[AuthenticationException HandleEventShutdownInitiatedByTransport`]
**Result validation:** :white_check_mark: Known issue matched with the provided build.
**Validation performed at:** 9/9/2026 6:11:46 PM UTC

### Report

|Build|Repository|Test|Pull Request|
|---|---|---|---|
|[1596749](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1596749)|dotnet/runtime|[System.Net.Http.Functional.Tests.WorkItemExecution](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1596749&view=ms.vss-test-web.build-test-results-tab&runId=44080014&resultId=219841)||
|[1596158](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1596158)|dotnet/runtime|[System.Net.Http.Functional.Tests.WorkItemExecution](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1596158&view=ms.vss-test-web.build-test-results-tab&runId=44066820&resultId=219852)|dotnet/runtime#133903|
|[1595150](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1595150)|dotnet/runtime|[System.Net.Quic.Tests.QuicListenerTests.Listener_BacklogLimitRefusesConnection_ParallelClients_ClientThrows](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1595150&view=ms.vss-test-web.build-test-results-tab&runId=44042440&resultId=162835)|dotnet/runtime#133571|
|[1594893](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1594893)|dotnet/runtime|[System.Net.Quic.Tests.QuicListenerTests.Listener_BacklogLimitRefusesConnection_ParallelClients_ClientThrows](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1594893&view=ms.vss-test-web.build-test-results-tab&runId=44029506&resultId=181428)|dotnet/runtime#133384|
|[1594346](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1594346)|dotnet/runtime|[System.Net.Quic.Tests.QuicListenerTests.Listener_BacklogLimitRefusesConnection_ParallelClients_ClientThrows](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1594346&view=ms.vss-test-web.build-test-results-tab&runId=44011536&resultId=181670)|dotnet/runtime#133800|
|[1593630](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1593630)|dotnet/runtime|[System.Net.Quic.Tests.MsQuicTests.ConnectWithCertificateForLoopbackIP_IndicatesExpectedError](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1593630&view=ms.vss-test-web.build-test-results-tab&runId=43988238&resultId=212081)|dotnet/runtime#133199|
|[1592143](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1592143)|dotnet/runtime|[System.Net.Http.Functional.Tests.WorkItemExecution](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1592143&view=ms.vss-test-web.build-test-results-tab&runId=43951894&resultId=219841)||
|[1591660](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1591660)|dotnet/runtime|[System.Net.Http.Functional.Tests.WorkItemExecution](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1591660&view=ms.vss-test-web.build-test-results-tab&runId=43935278&resultId=219841)||
|[1591266](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1591266)|dotnet/runtime|[System.Net.Http.Functional.Tests.WorkItemExecution](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1591266&view=ms.vss-test-web.build-test-results-tab&runId=43931480&resultId=219852)|dotnet/runtime#133366|
|[1591333](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1591333)|dotnet/runtime|[System.Net.Http.Functional.Tests.WorkItemExecution](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1591333&view=ms.vss-test-web.build-test-results-tab&runId=43929670&resultId=219841)||
|[1589475](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1589475)|dotnet/runtime|[System.Net.Http.Functional.Tests.WorkItemExecution](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1589475&view=ms.vss-test-web.build-test-results-tab&runId=43917736&resultId=219852)|dotnet/runtime#133513|
|[1588649](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1588649)|dotnet/runtime|[System.Net.Quic.Tests.QuicListenerTests.Listener_BacklogLimitRefusesConnection_ParallelClients_ClientThrows](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1588649&view=ms.vss-test-web.build-test-results-tab&runId=43851056&resultId=179757)|dotnet/runtime#133441|
#### Summary
|24-Hour Hit Count|7-Day Hit Count|1-Month Count|
|---|---|---|
|2|12|12|

Start with System.Net.Quic/src/System/Net/Quic/QuicConnection.cs at HandleEventShutdownInitiatedByTransport and trace the failure through QuicListener.cs. Run QuicListenerTests.Listener_BacklogLimitRefusesConnection_ParallelClients_ClientThrows and compare the repeated build reports. Done means the recurring test failure is understood and the affected test passes reliably without the reported AuthenticationException.

Written by the indexing model from the issue text.